1. Field of the Invention
The present invention relates to a display device, and more particularly to a display device and a manufacturing method thereof which enable a normal display by correcting a defective display such as point defects.
2. Description of the Related Art
A panel type display device such as a liquid crystal display device, an organic EL display device or the like includes a display region which is formed by stacking a plurality of films including an insulation film, a semiconductor film and a conductive film which are formed in a given pattern on an insulation substrate made of glass or the like. Particularly, with respect to an active matrix type display device which arranges a large number of pixels each having a switching element such as a thin film transistor or the like (an active element, hereinafter referred to as a thin film transistor) in a matrix array, in a manufacturing step of the substrate on which the above-mentioned thin film transistors and the like are arranged (a thin film transistor substrate), there arise defects attributed to mixing of foreign substances into films which constitute the thin film transistors, various wirings and various electrodes or to the deformation of pattern and these defects bring about a defective display.
A defective display (display defect) per pixel unit which occurs on the semiconductor film, the source electrode and the drain electrode which constitute the thin film transistor is referred to as a point defect, while with respect to a defect which causes short-circuiting or connection of lines which supply drive signals to thin film transistors, there may be a case in which a linear or strip-like display defect appears on a screen. The defects which are particularly large in number are point defects (defective lighting) and this defective lighting of the pixel degrades the quality of display images. Conventionally, to cope with the defective display attributed to such defects, processing which enables a normal image display by forming the defective pixel into a black point thus making the defective pixel less apparent, or by applying working (trimming) in which a deviating portion of a connected film or a connecting portion with a film of a neighboring pixel is removed to satisfy the design specification is conducted. However, when the number of the pixels which are formed into the black points is increased, the quality of the display screen as a whole is lowered. When the generated point defect is constituted of short-circuiting of the conductive films, the correction which separates a short-circuited conductive film by irradiating laser beams from an uppermost layer side of various films which are formed in a stacked manner is performed. Here, as literatures which disclose this type of related art, Japanese Unexamined Patent Publication 2000-347217, Japanese Unexamined Patent Publication Heill (1999)-38448 and Japanese Unexamined Patent Publication 2002-82346 can be named.